Professor Petteri Taalas, Director General of the Finnish Meteorological Institute (FMI) and former Secretary-General of the World Meteorological Organisation, sees the effects of climate change from his summer cottage on the shores of Lake Saimaa in eastern Finland.

He says this this summer has been exceptional – and worrying – in many ways.

Finland’s climate is warming significantly faster than the global average. Last year, the increase in the average global temperature exceeded the critical threshold of 1.5 degrees Celsius, according to the World Meteorological Organisation. In Finland, last year was 3.4 degrees warmer than pre-industrial levels.

Finland's faster warming is due to its location near the Arctic region. The melting of the Arctic snow and ice cover has accelerated warming, especially in northern regions, explains Taalas.

Taalas spoke about climate change and its impacts at the Savonlinna Climate Symposium last week.

Yle asked for his observations about this summer, which has brought some cooler days than usual as well as a record-breaking heatwave.

These are his four observations about this summer:

Heatwaves put a strain on bodies of water

Climate change is evident in this summer's exceptionally long heatwave.

Saturday was the 22nd consecutive day with a temperature reading over 30 degrees Celsius somewhere in Finland. The FMI reported readings of 30.4 degrees in Ranua, Finnish Lapland, and on Hailuoto Island near Oulu. It also issued a warning of severe heat in some central and northern parts of the country.

Heatwaves are putting a significant strain on waterways. During the hot weeks, river temperatures in various parts of Finland have risen to levels that are dangerously high for trout and Arctic grayling.

Fishing has been banned in some areas, such as Läsäkoski Rapids in Kangasniemi, South Savo, after the river temperature rose to 26 degrees. That is about two degrees warmer than the estimated maximum for fish survival.

Exceptional humidity

According to Taalas, there is now about 10 percent more moisture in the atmosphere than during previous average summers.

Climate change also increases the risk of heavy rainfall.

"When it rains, it may rain much more heavily than before. This creates challenges for buildings and infrastructure," Taalas warns.

In urban environments, the effects of heavy rainfall are particularly pronounced in areas with little vegetation. For example, the eastern city of Mikkeli experienced unprecedented flooding in July a year ago.

Climate change is making Finnish winters milder and wetter, as seen last winter. Winters have warmed faster than the summers, and winter precipitation increasingly comes down in the form of rain.

Wetter winters increase the humus content of water bodies, which leads to darkening of lake waters. At the same time, more nutrients are washed into water bodies from fields, raising the risk of toxic cyanobacteria, as known as blue-green algae.

Shallow lakes and endangered seals

Exceptionally low water levels have been reported in many of Finland's approximately 188,000 lakes.

The water level in the largest lake, Saimaa, is now about 80 centimetres lower than last summer. According to Taalas, the change is due to the fact that the traditional spring flood did not occur because of the mild winter.

"There will be fewer snowy, icy winters. The success of the Saimaa ringed seal depends on whether we can build auxiliary dens for the ringed seal or make artificial nests where they can give birth," Taalas says, referring to the highly endangered seal species that is endemic to Finland’s lake district.

And while climate change is boosting forest growth in some ways and extending the agricultural growing season, it also brings threats such as more destructive insect pests, he notes.